Laminated composite lens

ABSTRACT

The present invention is directed to a composite lens, comprising an anterior rigid gas permeable layer, and an annulus of soft material bonded to a posterior surface of the anterior rigid gas permeable layer, wherein a central zone of the composite lens is rigid and without a soft layer, wherein a peripheral zone of the composite lens is generally rigid in its anterior aspect and soft in its posterior aspect.

FIELD OF THE INVENTION

The present invention relates generally to laminated composite lenses,and more particularly to laminated composite lenses having an annulus ofsoft material bonded to the posterior surface of an anterior rigid gaspermeable layer.

BACKGROUND OF THE INVENTION

Refractive correction is achieved through use of spectacle lenses,contact lenses, corneal refractive surgery and intraocular lensimplantation. Contact lenses have evolved from non-gas-permeable rigidlenses which made contact with the sclera and vaulted the cornea, tocorneal contact lenses made of gas permeable products, and then tocorneal-scleral contact lenses made of hydrogel materials. Hybrid lenseswere created to provide the improved optics of rigid lenses with thecomfort of soft lenses. Conventional hybrid lenses were configured tohave a central rigid zone joined at a radial junction to a peripheralhydrogel zone.

Hybrid lenses of this configuration enjoy commercial success withlimitations due to the separation of the two materials at their radialjunction, lens flexure and tear stagnation due to a circumferentialsealing of the lens against the underlying eye. Advanced manufacturingprocesses and ultra high gas permeable materials have stimulated aresurgence of fully rigid scleral lens designs. Problems with suchdesigns include time consuming lens fitting, lens flexure, scleralimpingement, tear stagnation, persistent mid-peripheral bubbles anddifficulty in lens removal due to lens adherence.

US Patent Publication No. 2007/0291224 to Shui Lai discloses a lenshaving a contiguous soft back surface which is bonded to a contiguousrigid front surface. Such a composite lens presents difficulty due tothe loss of integrity of the optics due to irregularities caused by thebonding of the soft material to the rigid material in the optic zone ofthe lens. Further, the expansion of the soft material upon hydration ofas little as 1% is known to create stresses at the surface whichstimulate optical distortion and potential separation. Additionally, thesoft material is known to inter-penetrate the rigid material withresultant random changes in the index of refraction.

Reports of ideal lens-eye relationships with rigid scleral contactlenses detail the importance of having a clearance of between 10 and 100microns or more between the posterior lens surface and the anteriorcorneal surface. Hence, there is no clear need for hydrogel material inthe corneal portion of a laminated composite hybrid lens.

SUMMARY OF THE INVENTION

The present invention addresses the need for a composite hybrid lenshaving the advantages of a scleral contact lens with the addedadvantages of soft material in contact with the bulbar conjunctivacovering the sclera. Such a lens requires tear exchange, freedom fromscleral impingement, methods of managing flexure and air bubblesresulting from excessive clearance between the lens and the underlyingeye, and a release of the surface attraction which causes difficulty inlens removal due to adherence.

Various embodiments of the present invention are directed to a compositelens, comprising an anterior rigid gas permeable layer, and an annulusof soft material bonded to a posterior surface of the anterior rigid gaspermeable layer. A central zone of the composite lens is rigid andwithout a soft layer, while a peripheral zone of the composite lens isgenerally rigid in its anterior aspect and soft in its posterior aspect.In one implementation, the central zone of the composite lens is 7 mm to16 mm in diameter. In another implementation, the central zone of thecomposite lens is 10 mm to 13 mm in diameter. The annulus of softmaterial comprises a non-segmented annulus or a segmented annulus. Thecentral zone may be circular or non-circular. In one implementation, thecentral zone may be oval or elliptical. In another implementation, thecentral zone may have an irregular shape.

For segmented embodiments, the segmentation of the annulus serves as arelief for undesired expansion of the soft material on hydration, andprevents buckling or surface distortion due to expansion. The segmentedannulus comprises a plurality of segments separated by spaces betweensegments, wherein the spaces provide for exchange of fluids from a postlens tear reservoir, which forms under the anterior rigid gas permeablelayer. In addition, the spaces relieve lens-eye surface attraction,thereby facilitating lens removal. In some embodiment, (i) each segmentcomprises a sector of a peripheral portion of the lens ranging from 15degrees to 30 degrees, (ii) a width of each space is 10 microns to 1000microns, and (iii) a radial width of the soft annulus 2.5 mm to 5 mm.The thickness of the soft annulus may vary to accommodate scleralcontour. In one embodiment, the segments are uniform in shape. Inanother embodiment, the segments are irregular and non-uniform, and thespaces between the segments are irregular and vary in width from thecentral zone to the most peripheral portion of the soft annulus.

Another embodiment of the invention is directed toward a method formanufacturing a composite lens, comprising: (i) forming a rigid button;(ii) diamond turning a peripheral radius on a posterior portion of therigid button while sparing a central portion; (iii) mounting the buttonin a cup; (iv) treating an exterior surface of the rigid button; and (v)casting a selected soft lens material in the cup such that the soft lensmaterial is bonded to a curved posterior surface of the rigid lensmaterial. In some embodiments, the rigid portion may be molded into thedesired shape. The step of forming a rigid button may be performed byconventional casting in a cup or from sectioning of a rod of polymerizedmaterial. The method may further entail diamond turning a posteriorsurface of the composite lens to produce a desired posterior geometry.In addition, the method may comprise removing portions of the soft lensmaterial to form a soft peripheral annulus having a plurality ofsegments. The portions may be removed by diamond turning, milling, waterjet cutting or laser etching.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention, in accordance with one or more variousembodiments, is described in detail with reference to the followingfigures. The drawings are provided for purposes of illustration only andmerely depict typical or example embodiments of the invention. Thesedrawings are provided to facilitate the reader's understanding of theinvention and shall not be considered limiting of the breadth, scope, orapplicability of the invention. It should be noted that for clarity andease of illustration these drawings are not necessarily made to scale.

FIG. 1 is a cross-sectional view of a laminated composite lens, inaccordance with one embodiment of the present invention.

FIG. 2 is a side view of the laminated composite lens of FIG. 1, inaccordance with one embodiment of the invention.

FIGS. 3A-3F illustrate cross-sectional views of various segmentconfigurations of the soft posterior peripheral annulus of FIG. 1, inaccordance with the principles of the invention.

FIG. 4 is a cross-sectional view of a pre-formed button for making alaminated composite lens, in accordance with one embodiment of theinvention.

FIG. 5 is a cross-sectional view of a button for fabricating a hybridlens with an annulus of soft 510 on the ocular surface of rigidmaterial, in accordance with one embodiment of the invention.

FIG. 6 is a cross-sectional view of a finished lens fabricated from thebutton of FIG. 5, in accordance with one embodiment of the invention.

The figures are not intended to be exhaustive or to limit the inventionto the precise form disclosed. It should be understood that theinvention can be practiced with modification and alteration, and thatthe invention be limited only by the claims and the equivalents thereof.

DETAILED DESCRIPTION

In the following paragraphs, the present invention will be described indetail by way of example with reference to the attached drawings.Throughout this description, the preferred embodiment and examples shownshould be considered as exemplars, rather than as limitations on thepresent invention. As used herein, the “present invention” refers to anyone of the embodiments of the invention described herein, and anyequivalents. Furthermore, reference to various feature(s) of the“present invention” throughout this document does not mean that allclaimed embodiments or methods must include the referenced feature(s).

FIGS. 1 and 2 illustrate cross-sectional and side views, respectively,of a laminated composite lens 100 in accordance with the principles ofthe invention. Specifically, the composite lens 100 comprises ananterior rigid gas permeable layer 105 and an annulus 110 of softmaterial bonded to a posterior surface 115 of the anterior rigid gaspermeable layer 105. As such, a central zone 120 of the composite lens100 is rigid and without a soft layer, while a peripheral zone 125 ofthe composite lens 100 is generally rigid in its anterior aspect andsoft in its posterior aspect. The central zone 120 of the composite lens100 is about 3 mm to 20 mm in diameter, preferably about 7 mm to 16 mmin diameter, more preferably about 10 mm to 13 mm in diameter. Duringuse, the central zone 120 can approximate the horizontal diameter of thehuman or animal cornea upon which the composite lens 100 is applied.

According to various embodiments of the invention, the soft posteriorperipheral annulus 110 may be a complete, unbroken annulus or it may bea segmented annulus. In the illustrated embodiment, the annulus 110 issegmented and comprises 12 segments 130 substantially equivalent inshape and size. Any number of segments may be employed without departingfrom the scope of the invention. This segmentation serves as a relieffor undesired expansion of the soft material on hydration, and preventsbuckling or surface distortion due to expansion. The spaces 135 betweensegments 130 also provide for exchange of fluids from the post lens tearreservoir, which forms between the wearer's cornea and the central zone120 of the lens 100. Moreover, these spaces relieve the lens eye surfaceattraction which otherwise is a major cause of difficulty in lensremoval.

With further reference to FIGS. 1 and 2, each section 130 of thesegmented annulus 110 of soft material comprises a wedge or sector ofthe peripheral portion 125 of the composite lens 100. As illustrated,these wedges or sectors range from 1 degree to 180 degrees, preferablyfrom 5 degrees to 90 degrees, more preferably from 15 degrees to 30degrees. The space 135 between each sector ranges from approximately 1micron to 25000 microns, preferably from approximately 5 microns to12500 microns, more preferably from approximately 10 microns to 1000microns.

The thickness of the posterior peripheral annulus 110 is between about 2microns and 1000 microns, preferably between about 10 microns and 500microns, more preferably between about 40 microns and 200 microns. Inaddition, the thickness of the annulus 110 may not be uniform over thewidth of the annulus 110 and may vary to accommodate scleral contour.The relative elevation of the soft peripheral annulus 110 may be used toequalize scleral elevation differences. The central zone 120 of thecomposite lens 100 (containing only the gas permeable layer 105) may beformed as needed to meet a particular prescription. As such, thethickness of the gas permeable layer 105 may be variable across theoptic zone.

Some embodiments of the invention feature composite lenses having a softposterior annulus 110 bonded to a rigid gas permeable anterior layer 105having a total diameter of approximately 7 millimeters to 35millimeters, preferably approximately 10 millimeters to 22 millimeters,more preferably approximately 13 millimeters to 19 millimeters. Theradial width of the soft annulus 110 is about 0.25 millimeter to 10millimeters, preferably about 0.5 millimeters to 6 millimeters, morepreferably about 1 mm to 5 millimeters. The soft annulus 110 isconfigured to have a width that is substantially equivalent to theportion of the composite lens 100 which is anterior to the sclera of thewearer's eye. In some embodiments, the soft annulus 110 is also anteriorto a portion of the cornea-sclera junction and the cornea. Furtherembodiments of the invention feature a lens having a central rigidportion and a soft peripheral portion joined at a junction, but also hasa laminated composite feature with a soft annulus posterior to the rigidportion. In such embodiments, the soft annulus is adapted to lift therigid portion above the cornea. This is a function which is not possiblewith conventional hybrid lenses.

FIGS. 3A-3F illustrate cross-sectional views of various segmentconfigurations of the soft posterior peripheral annulus 110 of FIG. 1,in accordance with the principles of the invention. Specifically, FIG.3A depicts soft annulus 110 having substantially half-circular segments130 separated by spaces 135. In addition, FIG. 3B, illustrates arectilinear configuration of soft annulus 110 with rectangular segments130 and spaces 135, while FIG. 3C illustrates half-octagonal segments130 separated by spaces 135. In FIG. 3D, the segments 130 of softannulus 110 are rounded at the corners and the spaces 135 include sharpcorners, whereas in FIG. 3E, both the segments 130 and spaces 135 arerounded. Finally, in FIG. 3F, the alternating segments 130 and spaces135 of the soft annulus 110 form a substantially sinusoidal pattern. Aswould be appreciated by those of ordinary skill in the art, many othersoft posterior peripheral annulus 110 configurations are possiblewithout departing from the scope of the invention.

Methods of Manufacture

Referring to FIG. 4, the composite lenses described herein can be moldedor diamond turned from a pre-formed button 300 including soft lensmaterial 310 and rigid lens material 320. One exemplary method involves(i) forming a rigid button by conventional casting in a cup or fromsectioning of a rod of polymerized material, (ii) diamond turning aperipheral radius on the posterior portion of the button while sparingthe central portion, (iii) mounting the button in a cup, (iv) treatingthe surface of the rigid button, and (v) casting the desired soft lensmaterial 310 in the cup such that the soft lens material 310 is bondedto the curved posterior surface of the rigid lens material 320 in theperiphery of the button 300.

Since the central rigid lens material 320 will later be removed bydiamond turning, there is no need to have the soft lens material 310bonded to the central rigid material 320 at a radial junction.

Referring to FIGS. 1-4, the posterior surface 115 of the composite lens100 is diamond turned to produce a desired posterior geometry with themedial aspect of the soft peripheral annulus 110 transitioninganterior-ward to a pre-selected chord diameter where all the soft lensmaterial 310 is eliminated. In this manner, the peripheral aspect of thesoft peripheral annulus transitions anterior-ward to a preselected chorddiameter where the edge of the composite lens 100 is formed and all thesoft lens material 310 is eliminated.

According to some embodiments of the invention, the soft lens material310 is also removed to form segments 130 of the peripheral annulus 110,as depicted in FIG. 2. In other embodiments, a complete, unbroken (i.e.,non-segmented) annulus is employed without segmentation. In segmentedannulus embodiments, the material may be removed by diamond turning,milling, water jet cutting or laser etching.

The composite lens 100 is then blocked and the front surface is diamondturned in the conventional manner.

One skilled in the art would understand that the soft material could bemolded during its bonding process after the posterior surface of therigid layer was lathed to a final specification. Such molding couldimpart the segmented sector configuration to the soft peripheralannulus.

Referring to FIG. 5, a button 500 is depicted for fabricating a hybridlens with an annulus of soft material 510 on the ocular surface of rigidmaterial 520. Unlike conventional hybrid buttons, the button 500 of FIG.5 does not require a feature on the side of the button 500 that would bewithin the radial junction, and also does not require a curvilinearjunction or an angled junction. Instead, the junction of FIG. 5 can bestraight since the soft material 510 covering the back of the lensprovides the strength and increased surface area for the soft/rigidjunction.

FIG. 6 illustrates a finished lens 600 fabricated from the button 500 ofFIG. 5. In particular, the lens includes soft annulus portion 610 andrigid portion 620, wherein some of the rigid material 620 is removedbetween the two soft extensions 610. This space allows for a post lenstear layer, a feature that prevents the rigid material 620 fromcontacting and adhering to the cornea. In the illustrated embodiment,the soft annulus 610 is provided for the peripheral portion of the backof the rigid portion 620 of the lens 600.

One skilled in the art will appreciate that the present invention can bepracticed by other than the various embodiments and preferredembodiments, which are presented in this description for purposes ofillustration and not of limitation, and the present invention is limitedonly by the claims that follow. It is noted that equivalents for theparticular embodiments discussed in this description may practice theinvention as well.

While various embodiments of the present invention have been describedabove, it should be understood that they have been presented by way ofexample only, and not of limitation. Likewise, the various diagrams maydepict an example architectural or other configuration for theinvention, which is done to aid in understanding the features andfunctionality that may be included in the invention. The invention isnot restricted to the illustrated example architectures orconfigurations, but the desired features may be implemented using avariety of alternative architectures and configurations. Indeed, it willbe apparent to one of skill in the art how alternative embodiments maybe implemented to achieve the desired features of the present invention.Also, a multitude of different constituent part names other than thosedepicted herein may be applied to the various parts of the devices.Additionally, with regard to operational descriptions and method claims,the order in which the steps are presented herein shall not mandate thatvarious embodiments be implemented to perform the recited functionalityin the same order unless the context dictates otherwise.

Although the invention is described above in terms of various exemplaryembodiments and implementations, it should be understood that thevarious features, aspects and functionality described in one or more ofthe individual embodiments are not limited in their applicability to theparticular embodiment with which they are described, but instead may beapplied, alone or in various combinations, to one or more of the otherembodiments of the invention, whether or not such embodiments aredescribed and whether or not such features are presented as being a partof a described embodiment. Thus the breadth and scope of the presentinvention should not be limited by any of the above-described exemplaryembodiments.

Terms and phrases used in this document, and variations thereof, unlessotherwise expressly stated, should be construed as open ended as opposedto limiting. As examples of the foregoing: the term “including” shouldbe read as meaning “including, without limitation” or the like; the term“example” is used to provide exemplary instances of the item indiscussion, not an exhaustive or limiting list thereof; the terms “a” or“an” should be read as meaning “at least one,” “one or more” or thelike; and adjectives such as “conventional,” “traditional,” “normal,”“standard,” “known” and terms of similar meaning should not be construedas limiting the item described to a given time period or to an itemavailable as of a given time, but instead should be read to encompassconventional, traditional, normal, or standard technologies that may beavailable or known now or at any time in the future. Likewise, wherethis document refers to technologies that would be apparent or known toone of ordinary skill in the art, such technologies encompass thoseapparent or known to the skilled artisan now or at any time in thefuture.

A group of items linked with the conjunction “and” should not be read asrequiring that each and every one of those items be present in thegrouping, but rather should be read as “and/or” unless expressly statedotherwise. Similarly, a group of items linked with the conjunction “or”should not be read as requiring mutual exclusivity among that group, butrather should also be read as “and/or” unless expressly statedotherwise. Furthermore, although items, elements or components of theinvention may be described or claimed in the singular, the plural iscontemplated to be within the scope thereof unless limitation to thesingular is explicitly stated.

The presence of broadening words and phrases such as “one or more,” “atleast,” “but not limited to” or other like phrases in some instancesshall not be read to mean that the narrower case is intended or requiredin instances where such broadening phrases may be absent.

The invention claimed is:
 1. A composite button for manufacturing acomposite lens, the button comprising: a rigid lens material formed bycasting; an annulus of soft lens material on an ocular surface of therigid material; wherein the soft lens material is bonded to the rigidlens material; and wherein the soft lens material transitionsanterior-ward to the rigid lens material at a preselected chord diameterwhere the edge of the composite lens is to be formed.
 2. The button ofclaim 1, wherein a lateral junction between the soft lens material andthe rigid lens material is substantially straight.
 3. The button ofclaim 1, wherein the soft lens material is bonded to a periphery of therigid lens material.
 4. The button of claim 1, wherein a central zone ofthe button is rigid and without a soft layer.
 5. The button of claim 1,wherein a peripheral zone of the button is rigid in its anterior aspectand soft in its posterior aspect.
 6. The button of claim 5, wherein thesoft lens material forms an annulus posterior to the rigid lensmaterial, and wherein said annulus extends below the rigid lens materialsuch that the rigid lens material is lifted anterior to the cornea whenthe composite lens is applied to an eye.